Siskiyou aster

not listed

NNR - Unranked

SNR - Unranked

not listed

FACW - Facultative wetland

FAC - Facultative

FACW - Facultative wetland

Siskiyou aster (var. hesperium) is a 12″ to 60″ tall, erect, perennial forb that rises on a single stem from a long, slender, branched rhizome. It sometimes forms large, dense colonies.

The stem is erect, straight, stout, and grooved. It is unbranched below the middle. It is green at first, eventually becoming brown and woody near the base. Above the middle it usually has many, sometimes just a few, spreading, ascending branches. It is usually hairless toward the bottom and may have sparsely to moderately dense, longitudinal lines of short, white, spreading or curled hairs toward the top.

Basal leaves are stalkless. The leaf blades are thin, inversely lance-shaped or inversely egg-shaped, up to 3⅛″ long, and up to ¾″ wide. They are tapered at the base, and rounded or angled at the tip. There is a short, sharp, abrupt point at the tip. The upper and lower surfaces are hairless. The margins are toothed with rounded, forward-pointing teeth, and have a fringe of hairs. Basal leaves are usually withered at flowering time.

Stem leaves are alternate. Lower stem leaves are stalkless or on short, winged, poorly differentiated leaf stalks (petioles). The petioles are winged and sheath the stem at the base. The leaf blades are linear lance-shaped to inversely lance-shaped, 2″ to 6″ long, and ⅜″ to ¾″ wide. They are wedge-shaped or tapered and sometimes slightly expanded at the base, but they do not clasp the stem. They taper to a point at the tip. The upper and lower surfaces are hairless. The margins are shallowly toothed. The leaves become progressively smaller, narrower, and shorter-stalked as they approach the middle of the stem. Middle and upper stem leaves are untoothed. Upper stem leaves are stalkless, linear, and 1¼″ to 4″ long, not much smaller than the middle stem leaves. Lower stem and sometimes some of the larger middle stem leaves are withered by flowering time.

The inflorescence is a branched cluster (panicle) at the end of the stem. The primary branches of the panicle are relatively sparse, loosely ascending or spreading, and sometimes solitary or more often clustered near the end of the vegetative branch. The flower heads are closely spaced, appearing dense, on lateral, secondary branches. The heads are usually oriented in various directions, sometimes oriented toward the top of the branch. The flower heads are on 3 ⁄16″ to 2″ long flower stalks (peduncles). They are usually subtended by leaf-like appendages (bracts). The leaves on the flowering branches are often longer than the peduncles, but are much smaller than the upper stem leaves.

The individual flower head is medium-sized, ¾″ to 1″ in diameter. The whorl of bracts (phyllaries) at the base of the flower head form a cup-shaped, ⅛″ to ¼″ long cup (involucre). The phyllaries are arranged in 3 to 5 appressed to slightly spreading, overlapping series. They do not have a spine-like tip. Phyllaries in the outer series are ⅔ as long or longer than those of the inner series. There are 18 to 45 ray florets and 18 to 52 disk florets. The ray florets are in 1 or 2 series. They are ⅛″ to ⅜″ long and usually pale to dark purplish-blue, sometimes white. The disk florets are yellow at first, eventually becoming purple. The flowers are not fragrant.

The fruit is a dry seed capsule (cypsela) with a tuft of bristles (pappus) attached to the end. The cypsela is egg-shaped, gray to tan, and 1 ⁄32″to 1 ⁄16″ long. It has 4 or 5 longitudinal ribs. The pappus is white to off-white.

12″ to 60″

Purplish-blue

Eastern panicled aster (Symphyotrichum lanceolatum ssp. lanceolatum) heads are not subtended by large, leaf-like bracts. Phyllaries in the outer series are ⅓ to ⅔ as long as those of the inner series.

Moist. Stream banks, wet meadows, and ditches. Full sun to partial shade.

July to October

Sources

3, 28.

Native

This and other asters were formerly place in the genus Aster. That genus was problematic, in that it did not include just one common ancestor with all of its lineal descendants and no others – it was not monophyletic. In 1994, the genus Symphyotrichum was resurrected to include most North American asters formerly in the genus Aster.

This is a variety of a subspecies, and some sources list it as Symphyotrichum lanceolatum ssp. hesperium var. hesperium. The ICN (International Code of Nomenclature for algae, fungi, and plants), the rules governing the naming of plant species, makes it clear that this is not correct. Following ICN rules, a taxa “may also be referred to” with the inclusion of the intervening name (in this case, “ssp. hesperium”), but that does not constitute a formal name.